Biomedical subjects
Publications and source records attributed to S Shany.
During an epidemic of measles, 12 young adults developed hypocalcemia associated with a decrease in parathyroid hormone level. Calcium and parathyroid hormone levels returned to normal in five of the 12 patients for whom convalescent data were available.
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The major metabolites of vitamin D, 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D were assayed in the blood of mothers at delivery and in the cord blood of their infants. Twelve Bedouin women and nine Jewish women were investigated; all lived in the Negev desert in Israel. All three vitamin D metabolites were significantly lower in cord than in maternal blood in both groups. Bedouin mothers and infants had significantly lower levels of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D than did Jewish mothers and infants. Concentrations of 1,25-dihydroxyvitamin D did not differ significantly between the ethnic groups and in both maternal groups were well above the normal range (Bedouins 83.6 pg/ml +/- 11.3; Jews 98.6 pg/ml +/- 12.3). Cord and maternal values for this metabolite were significantly correlated (r = 0.71, p less than 0.001).
We measured peritoneal losses of the active vitamin D metabolites 1,25(OH)2D3 and 24,25(OH)2D3 in patients receiving continuous ambulatory peritoneal dialysis (CAPD). The serum concentration of 24,25(OH)2D3 was considerably lower than in hemodialysis patients. The serum concentration of 1,25(OH)2D3 was undetectable and rose to levels similar to those in hemodialysis patients only after loading with much higher oral doses of 1-alpha-vitamin D3 than those received by hemodialysis patients. Losses of both metabolites in peritoneal fluid were considerable, averaging approximately 6-8% of the plasma pool per day. These losses lead to low serum levels of these active vitamin D metabolites in CAPD patients, which may be an important factor in exacerbating renal osteodystrophy. Our results indicate the need for increased replacement doses of vitamin D metabolites in CAPD patients.
The role of oestradiol-17 beta in the induction of specific cytosolic receptors for 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) was examined in the immature rat uterus. An acrylamide gel electrophoretic analysis was developed to separate the specific receptor for 1,25(OH)2D3 from the plasma binding protein for vitamin D3 metabolites. Employing this sensitive method the presence of receptors for 1,25(OH)2D3 in the mature rat uterus was evident. Such receptors were not found in the uterus of saline-treated immature rats. However, oestradiol administration caused an induction of these receptors in the immature rat uterus, together with a significant increase in the uterine weight, progesterone receptor level and peroxidase activity. These results suggest a mechanism for oestradiol regulation of calcium metabolism in the uterus at times of high demand for this cation during the gestation period.
An experimental fracture in a dog with chorea was found to heal faster, and with a larger callus, than normal. Serum levels of parathormone (PTH), calcitonin (CT) and vitamin D metabolities were determined during callus formation. Serum concentrations of vitamin D metabolites were lower from the beginning while serum CT levels were higher compared to normal dogs. A massive increase in serum levels of 24,25-dihydroxyvitamin D was noted during the healing period. These results and observations suggest the existence of some disturbances in the secretion of hormones regulating calcium metabolism during bone repair where a nervous system lesion exists.
The metabolism of calcium is regulated by hormones: parathyroid hormone, (PTH) calcitonin (CT), and vitamin D metabolites. To study the physiologic role of these hormones during the process of fracture healing in humans, the blood levels of PTH, CT, 25-(OH)-D3, 24,25-(OH)2-D3, and calcium were determined in 13 young patients with fractures of long bones. The parameters were measured first on admission and again after six to eight weeks. A group of healthy volunteers of similar age and sex served as control subjects. Plasma calcium level on the day of fracture was significantly reduced, 8.50 +/- 0.23 mg% (p less than 0.001). Serum CT level on the day of fracture was significantly increased, 0.18 +/- 0.02 ng/ml (p less than 0.05), and it continued to increase during the healing period, up to 0.23 +/- 0.02 ng/ml (p less than 0.001) after six to eight weeks. A significant rise was noted in plasma level of 24,25-(OH)2-D3, from 2.02 +/- 0.42 ng/ml on the day of fracture to 2.84 +/- 0.41 ng/ml six weeks later (p less than 0.05). No significant changes were found in serum PTH and plasma 25-(OH)-D3 levels on the day of fracture or during the healing process. The results suggest a possible physiologic active role for CT and 24,25-(OH)2-D3 in fracture healing in humans.
1. Rats were fed various diets ranging from the normal chow, pure flour containing large amounts of phytic acid, Ca-enriched flour and mixtures of flour and normal food with various levels of calcium. 2. It was found that the animals eating the pure flour grew less and were smaller. 3. They suffered from hypocalcemia and had low plasma alkaline phosphatase and 25-HCC-vitamin D3 levels. 4. These animals had rib-cage deformities. 5. Additional calcium in the flour improved the animals' growth and calcification. 6. The mixed food did not greatly affect the animals and additional calcium did not improve growth or bone mineralisation. 7. The Bedouin eat large amounts of unleavened bread containing large amounts of phytates. 8. It is concluded that uptake of large amounts of phytates by the Bedouin eating unleavened bread is due to the flour and that the clinical manifestations are a direct result of the flour and not the lack of vitamin D due to covering the skin from sunlight.
25 Hydroxycholecalciferol levels were measured in eight Beduin mothers in labor and in the cord blood of their infants, and compared with values in 42 Sephardi Israeli women in labor and the cord blood of their offspring. Beduin baby cord blood had a mean 25 hydroxycholecalciferol concentration of 3.78 ng/ml +/- 3.22 (SD) being about half of their mothers' level in labor. Values in Sephardi women and cord blood were 3 times higher. PTH levels were lower and calcium concentrations were higher in cord blood (P less than 0.001) in both groups when compared to their mothers' blood. The relevance of these findings to the high incidence of infantile rickets and hyypocalcemia in Beduin children is discussed.
1. The plasma levels of 25-hydroxycholecalciferol were measured in female dromedary camels, female sheep and Sinai desert goats. 2. The camels had levels of 443 +/- 96 ng/ml in summer, and 267 +/- 113 ng/ml in winter. 3. The sheep had levels of 40.7 +/- 9.09 ng/ml in summer and 37.1 +/- 8.82 ng/ml in winter, i.e. roughly the same as man in that region. 4. The goats had lower levels: 23.9 +/- 5.67 ng/ml in summer.
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In a series of 18 patients suffering from varying degrees of chronic renal failure treated by diet alone, there was a statistically significant positive correlation between plasma magnesium levels and plasms 25 hydroxycholecalciferol (25 HCC) levels. This is thought to be due either to the direct action of 25 HCC on the bone liberating magnesium from bone crystal, or to an increased intestinal absorption of magnesium caused by 25 HCC.
25-Hydroxycholecalciferol (25-HCC) levels were measured in 31 bedouin females and eight bedouin male tribesmen and compared with the levels in Jewish males and females in Beersheba. In nonpregnant bedouin women the mean 25-HCC level was 25.4 ng/ml +/- 9.78. In pregnant bedouin women the mean was 23.4 ng/ml +/- 8.52. In bedouin males the mean level was 25.7 ng/ml +/- 3.03. In Jewish females, both pregnant and nonpregnant, the levels were higher (32.7 ng/ml +/- 6.02 and 44.3 ng/ml +/- 9.24). Jewish males had levels of 32.8 +/- 6.29 ng/ml. No bedouin had plasma levels below 10 ng/ml, and there was no evidence to suggest deficiency of vitamin D in bedouin males or females.
Highly purified streptococcal nicotinamide adenine dinucleotide glycohydrolase (NADase) was obtained by utilizing disodium tetrathionate to protect the enzyme by blocking the sulfhydryl groups of streptococcal proteinase. This was followed by two-step ion-exchange chromatography. The pure enzyme, demonstrated as a single band on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, had a specific activity of 11,200 NADase units per mg of protein and was devoid of hemolytic activity. NADase had a molecular weight of about 55,000 as determined by gel filtration, by summation of amino acid residues, and by sodium dodecyl sulfate/gel electrophoresis. The purified enzyme had optimal activity at pH 7.3 and at 40 C and a calculated Km of 5.1 times 10- minus 4 mM. It was inhibited by alpha-iodoacetamide.
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Streptococcal nicotinamide adenine dinucleotide glycohydrolase (NADase) with a molecular weight of about 55,000 and an isoelectric pH of 8.55 was isolated from crude streptolysin O (SLO) preparations. NADase differed from SLO in size, charge, and immunological behavior. Streptococcal NADase is considered to have no role in the hemolytic process because it has no hemolytic activity; conversely, partially purified SLO showed no NADase activity. The hemolytic activity of crude SLO was completely inhibited by anti-tetanolysin, whereas the NADase activity in the same reaction mixture was unaffected. Experiments involving double diffusion in agar also demonstrated immunological nonidentity of the two proteins.